Technique for providing dynamic modification of application specific policies in a feedback-based, adaptive data network

ABSTRACT

A feedback-based adaptive network is described wherein at least a portion of the network elements report operating information relating to network conditions to a centralized data store. The information which is reported to the data store is analyzed by a policy engine, and updated control information may be generated. The updated control information may be fed back to selected network elements to thereby affect operation of the selected elements. In this way, the dynamic and automatic feedback control of network elements is provided. Events relating to changing conditions in the network may also be reported to selected elements. Additionally the adaptive, feedback-based network may include a network quality monitoring system for evaluating performance characteristics or other aspects of the network. If it is determined that a particular characteristic of the network does not conform with the standards established for that characteristic, the policy which controls that particular characteristic of the network may be automatically and dynamically modified to thereby affect the network performance.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.10/821,285, entitled “TECHNIQUE FOR PROVIDING DYNAMIC MODIFICATION OFAPPLICATION SPECIFIC POLICIES IN A FEEDBACK-BASED, ADAPTIVE DATANETWORK” by Natarajan et al., filed on Apr. 9, 2004, which is acontinuation of now Ser. No. 09/342,341, now U.S. Pat. No. 6,765,864,entitled “TECHNIQUE FOR PROVIDING DYNAMIC MODIFICATION OF APPLICATIONSPECIFIC POLICIES IN A FEEDBACK-BASED, ADAPTIVE DATA NETWORK” byNatarajan et al., filed on Jun. 29, 1999, and from each of whichpriority is claimed pursuant to the provisions of 35 U.S.C. 120. Each ofthese applications is incorporated by reference herein for all purposes.

This invention is related to U.S. Pat. No. 6,539,427, issued on Mar. 25,2003, naming Shankar Natarajan, Andrew G. Harvey, Hsuan-Chung Lee, VipinRawat, and Leo Pereira as inventors, and entitled “Dynamically AdaptiveNetwork Element in a Feedback-Based Data Network”. That application isincorporated herein by reference in its entirety and for all purposes.

This invention is related to U.S. Pat. No. 6,505,244, issued on Jan. 7,2003, naming Shankar Natarajan, Andrew G. Harvey, Hsuan-Chung Lee, VipinRawat, and Leo Pereira as inventors, and entitled “Policy Engine whichSupports Application Specific Plug-ins for Enforcing Policies in aFeedback-Based, Adaptive Data Network”. That application is incorporatedherein by reference in its entirety and for all purposes.

This invention is related to U.S. Pat. No. 6,577,597, issued on Jun. 10,2003, naming Shankar Natarajan, Andrew G. Harvey, Hsuan-Chung Lee, VipinRawat, and Leo Pereira as inventors, and entitled “Dynamic Adjustment OfNetwork Elements Using A Feedback-Based Adaptive Technique”. Thatapplication is incorporated herein by reference in its entirety and forall purposes.

This invention is related to U.S. patent application Ser. No.09/342,742, filed on Jun. 29, 1999, naming Shankar Natarajan, Andrew G.Harvey, Hsuan-Chung Lee, Vipin Rawat, and Leo Pereira as inventors, andentitled “Technique for Collecting Operating information from NetworkElements, and for Controlling Network Element Behavior in aFeedback-Based, Adaptive Data Network”. That application is incorporatedherein by reference in its entirety and for all purposes.

This invention is related to U.S. Pat. No. 6,584,502, issued on Jun. 24,2003, naming Shankar Natarajan, Andrew G. Harvey, Hsuan-Chung Lee, VipinRawat, and Leo Pereira as inventors, and entitled “Technique forProviding Automatic Event Notification of Changing Network Conditions toNetwork Elements in an Adaptive, Feedback-Based Data Network”. Thatapplication is incorporated herein by reference in its entirety and forall purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to data networks, and morespecifically to a technique for providing a feedback-based data networkfor dynamically adapting to changing network conditions.

2. Background

The merging of computers and communications has had a profound influenceon the way computer systems are organized. As computer technologyadvances, the role of computer networks steadily increases. Varioustypes of computer networks include internetworks (e.g., the Internet),local area networks (LANs), metropolitan area networks (MANs), and widearea networks (WANs).

The use of networks such as LANs or WANs allows data or otherinformation to be exchanged over large distances at a reasonable speed,and at relatively low cost. Although conventional network systems areadvantageous for a variety of reasons, implementing and maintaining suchnetworks presents an ongoing problem. Moreover, a network may span aplurality of separate LANs and/or WANs to create the impression of aunified network. This has greatly complicated the implementation,maintenance, and control of system parameters within the network.

As the use of computer networks proliferates, there exists an increasingneed to improve computer network designs and implementations in order tofacilitate the management, implementation, and modification of suchnetworks.

SUMMARY OF THE INVENTION

According to specific embodiments of the invention, a technique isprovided for implementing a feedback-based data network which is able toautomatically and dynamically monitor characteristics of various aspectsof the network and adapt to changing network conditions by dynamicallyand automatically modifying selected network parameters in order toachieve a desired performance level.

According to specific embodiments of the present invention, a method andcomputer program product are disclosed for providing dynamic feedbackcontrol of network elements in a data network. Each of the networkelements has a plurality of operating parameters associated therewith.The operating parameters associated with a particular network elementare related to at least one control parameter of that element.Information related to a first subset of network elements is retrieved.At least a portion of the retrieved information is then analyzed usingselected guidelines to determine whether a performance of at least aportion of the network conforms with predetermined criteria. Thepredetermined criteria may be related to desired quality characteristicsof the network, predetermined Service Level Agreement parameters, faultmanagement performance, network security, billing information, etc. Theresults of the analysis are then automatically reported to anadministrator or administration system for handling, and/or respondingto the reported results.

Alternative embodiments of the present invention are directed to amethod and computer program product for providing dynamic feedbackcontrol of network elements in a data network. Each of the networkelements has a plurality of operating parameters associated therewith.The operating parameters associated with a particular network elementare related to at least one control parameter of that element. Thenetwork further includes a policy engine having at least one policy foranalyzing information from selected network elements and dynamicallygenerating updated control information used to affect at least oneaspect of network performance. Information related to a first subset ofnetwork elements is retrieved. At least a portion of the retrievedinformation is then analyzed to determine whether the policy is beingeffective in causing at least one aspect of network performance toconform with predefined performance criteria. In response to adetermination that the policy is not effective in causing the aspect ofnetwork performance to conform with the predefined performance criteria,the policy is dynamically modified. Further, an additional aspect ofthis embodiment provides that the dynamic modification of the policy isimplemented automatically in response to a determination that the policyis not being effective in causing the aspect of network performance toconform with the predetermined performance criteria.

A further embodiment of the present invention is directed to amonitoring system for providing dynamic feedback control of networkelements in a data network. Each of the network elements has a pluralityof operating parameters associated therewith. The operating parametersassociated with a particular network element are related to at least onecontrol parameter of that element. The monitoring system comprises atleast one CPU, memory, and at least one interface for retrievinginformation related to a first subset of network elements. Themonitoring system is operable to analyze at least a portion of theretrieved information based upon selected guidelines to determinewhether a performance of at least a portion of the network conforms withpredetermined criteria. The monitoring system is further operable toreport the results of the analysis to an administrator or anadministration system for responding to the reported results.

An additional embodiment of the present invention is directed to amonitoring system for providing dynamic feedback control of networkelements in a data network. Each of the network elements has a pluralityof operating parameters associated therewith. The operating parametersassociated with a particular network element are related to at least onecontrol parameter of that element. The network further includes a policyengine having at least one policy for analyzing information fromselected network elements and dynamically generating updated controlinformation used to affect at least one aspect of network performance.The monitoring system comprises at least one CPU, memory, and at leastone interface for retrieving information related to a first subset ofnetwork elements. The monitoring system is operable to analyze at leasta portion of the retrieved information to determine whether the policyis effective in causing at least one aspect of network performance toconform with predefined performance criteria. The monitoring system isfurther operable to cause the policy to be modified in response to adetermination that the policy is not effective in affecting the aspectof network performance to conform with the predefined performancecriteria.

Alternative embodiments of the present invention are directed to amethod and computer program product for providing dynamic feedbackcontrol of network elements in a data network. Each of the networkelements has a plurality of operating parameters associated therewith.The operating parameters associated with a particular network elementare related to at least one control parameter of that element. Thenetwork further includes a policy engine having at least one policy foranalyzing information from selected network elements and dynamicallygenerating updated control information used to affect at least oneaspect of network performance. Information is received relating to aneffectiveness of a specified policy of said policy engine in causing anaspect of network performance to conform with predefined performancecriteria. The specified policy is dynamically modified in response to adetermination that the policy is not effective in causing the aspect ofnetwork performance to conform with the predefined performance criteria.In a specific embodiment, the dynamic modification of the policy may beimplemented automatically.

An alternative embodiment of the present invention is directed to anadministration system for providing dynamic feedback control of networkelements in a data network. Each of the network elements has a pluralityof operating parameters associated therewith. The operating parametersassociated with a particular network element are related to at least onecontrol parameter of that element. The network further includes a policyengine having at least one policy for analyzing information fromselected network elements and dynamically generating updated controlinformation used to affect at least one aspect of network performance.The administration system comprises at least one CPU, memory, and atleast one interface operable to receive information relating to aneffectiveness of a specified policy of the policy engine in causing anaspect of network performance to conform with predefined performancecriteria. The administration system is operable to dynamically modifythe policy in response to a determination that the policy is noteffective in causing the aspect of network performance to conform withthe predefined performance criteria. Further, the dynamic modificationof the policy may be automatically implemented by the administrationsystem.

Additional features and advantages of the present invention will becomeapparent from the following descriptions of its preferred embodiments,which descriptions should be taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a schematic block diagram of a conventionalframe relay network 150.

FIG. 2 shows a schematic block diagram of a specific embodiment of thefeedback-based, adaptive data network of the present invention.

FIG. 3 shows a schematic block diagram of the adaptive feedback-baseddata network of FIG. 2, implemented as a frame relay network.

FIG. 4 shows a schematic block diagram of an alternate embodiment of thefeedback-based, adaptive data network of the present invention.

FIG. 5A shows a schematic block diagram of a router 10 which may beimplemented as a network element in accordance with the feedback-based,adaptive data network of the present invention.

FIG. 5B shows a schematic block diagram of data store 252 of FIG. 2, inaccordance with a specific embodiment of the present invention.

FIG. 5C shows a schematic block diagram of policy engine 254 of FIG. 2,in accordance with a specific embodiment of the present invention.

FIG. 6 shows an example of a flow diagram of an initialization procedurefor initializing the network of FIG. 2.

FIG. 7 shows a flow diagram of an event registration procedure 700 inaccordance with a specific embodiment of the present invention.

FIG. 8 shows a flow diagram of a network element reporting procedure 800in accordance with a specific embodiment of the present invention.

FIG. 9A shows a flow diagram of an event notification procedure 900A inaccordance with a specific embodiment of the present invention.

FIG. 9B shows a flow diagram of an event notification response procedure900B in accordance with a specific embodiment of the present invention.

FIG. 10 shows a flow diagram of a network element parameter updateprocedure 1000 in accordance with a specific embodiment of the presentinvention.

FIG. 11 shows a specific embodiment of a flow diagram of a policy engineanalysis procedure 1100, which may be implemented by the policy engine254 of FIG. 2.

FIG. 12 shows a flow diagram example of a frame relay CIR policy 1200which may be implemented by procedure 1100 of FIG. 11.

FIG. 13 shows a specific embodiment of a flow diagram for implementing anetwork performance quality monitor procedure 1300, which may beimplemented by monitor system 262 of FIG. 2.

FIG. 14 shows a specific embodiment of a flow diagram for implementingan administration procedure 1400, which may be implemented by ADMINsystem 260 of FIG. 2.

FIG. 15 shows an example of a flow diagram for implementing a data storeevent handler reporting procedure 1500, which may be implemented by datastore 252 of FIG. 2.

FIGS. 16-18 illustrate schematic diagrams and flow diagrams, showing, byway of example, how the feedback-based adaptive network of the presentinvention may be implemented in a network for automatically adapting tochanges in network conditions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an example of a frame relay network. The frame relaynetwork may be thought of as comprising a group of frame relay virtualcircuits for transmitting data between a first user/computer system anda second user/computer system. A frame relay virtual circuit representsa high-speed packet switching path used in wide area networks. It hasbecome very popular for LAN to LAN connections across remote distances.A consumer may lease a frame relay virtual circuit between two pointsand send packets of information between the two points. It is alsopossible to lease frame relay circuits between a given site and multipleother sites.

As shown in FIG. 1, a frame relay network with one frame relay virtualcircuit 150 connects a client computer 102 with a server 114. Typicallya service provider charges for access at both ends of the network. Whenleasing the frame relay virtual circuit, the consumer agrees to pay aspecified amount of money in return for the service providerguaranteeing a time-averaged bandwidth for the virtual circuit.

One difference between a physical leased line and a frame relay circuitis that, with the physical leased line, a user pays for a specifiedamount of bandwidth, and may send traffic all day long at the maximumspeed. However, with a virtual circuit, data bursts may be sent at fullspeed, but the long-term average usage (i.e., committed information rateor CIR) must be at or above a predetermined level.

Typically, when a client is provisioned a virtual circuit, a serviceprovider will guarantee to provide a minimum amount of bandwidth forhandling client traffic. More specifically, the consumer pays for, andthe service provider agrees to provide, a virtual circuit which is ableto handle a specified committed burst size (Bc) of data (e.g. Bc=256Kbits) over a specified committed time interval (Tc) (e.g. Tc=1 second).The value Bc/Tc is referred to as the committed information rate (CIR),which specifies the rate at which the virtual circuit will accept datafrom the consumer. In the example above, the CIR value is equal to 256Kbits/sec, meaning that over the span of one second, the service providerguarantees to handle 256 Kbits of data.

At times, however, a client may be running an application which requiresmore than 256K bits/sec of bandwidth. For example, the client may berequired to send bursts of traffic at 300K bits/sec from time to time.Although the CIR value represents the average guaranteed bandwidth forthe virtual circuit, the service provider also provides an allowance fordata bursts. This allowance is referred to as the excess burst size (Be)(e.g. Be =64 Kbits). Thus, using the example above, in time Tc (1second), the Bc value (256K) may be exceeded by Be (64K) without thecustomer having to pay. This amount of additional bandwidth is referredto as the excess information rate (EIR=Be/Tc), and represents the excessbandwidth which the service provider will attempt to deliver to theconsumer. Any data sent by the consumer in excess of the EIR value willbe dropped. Further, data bursts which are between the Bc and Be valuemay be discarded in the event of network congestion.

The frame relay virtual circuit 150 of FIG. 1 comprises a plurality ofindividual network elements (e.g., 104A, 104B, 108) which are part of awide area network. Typically, different portions of the wide areanetwork are owned and/or managed by separate entities. For example, theservice provider may manage or control the gateways (104A, 104B) foraccessing the wide area network from either the client machine 102 orserver machine 114. More typically, however, the gateways are controlledby the end user who has the ability to reconfigure these devices.Gateway devices 104A and 104B may, in turn, communicate with frame relaycloud 110, which may be managed or controlled by a separate entity suchas, for example, a data network company (e.g., AT&T, MCI, Sprint, etc.).Typically, the frame relay service provider and the frame relay carrierare the same entity.

In the example of FIG. 1, devices 104A and 104B represent frame relaydevices, such as, for example, routers which are configured to handleframe relay protocol. Each of the frame relay devices 104A, 104B aretypically statically configured by a system administrator using acommand line interface (CLI) via a local console (106A, 106B,respectively). Each terminal 106A, 106B is connected directly to itsrespective Frame relay device via a local console port (not shown) atthe device. The virtual circuit between frame relay device 104A andframe relay device 104B is provided by the FR cloud network 110,maintained and controlled by the frame relay service provider. The FRcloud includes a plurality of switching devices (108) which arestatically configured by a system administrator to provide virtualcircuits, each circuit having a specified CIR and EIR value. When aservice provider provisions a virtual circuit having specific CIR andEIR values, a human technician is hired to provision the circuit bystatically configuring specific network elements within the cloud toform the desired communication path having the specified CIR and EIRvalues.

Conventionally, the provisioning of a virtual circuit by a serviceprovider requires not only manual configuration of frame relay devices104A, 104B, but also requires coordination between the end user and theservice provider which manages the FR cloud 110. This coordinationusually takes place by sending a request to the service provider toimplement or modify a virtual circuit within FR cloud 110. Once therequest is received by the service provider, it is handled manually by aservice technician who statically configures the various switches andother devices within the FR cloud 110 to implement a virtual circuithaving specified CIR and EIR values. Because of the manual stepsinvolved, it is not uncommon for days to pass before the consumer (e.g.,client 102) is able to use the virtual circuit.

Moreover, significant delays may be experienced when attempting tomodify or reconfigure parameters associated with a virtual circuit. Forexample, let us suppose that the consumer initiates a video conferencingapplication between client 102 and server 114. Further, let us supposethat the current CIR and EIR bandwidth values for virtual circuit 150are insufficient for supporting high quality video/voice applications,resulting in the client 102 receiving poor quality video images andvoice information from server 114. In order to overcome this problem, ahuman operator at the client side may send a request to the serviceprovider to increase the CIR value for the virtual circuit 150.

However, in order to increase the CIR and/or EIR values on the virtualcircuit 150, a plurality of network elements within the WAN which formthe communication path between client machine 102 and server 114 must bestatically reconfigured by a human operator to support the new CIR andEIR values. Thus, when the request from the human operator at clientside is received at the service provider end, a system administrator orother service technician must statically reconfigure each of the networkelements which form the virtual circuit connecting client 102 withserver 114. This may include statically reconfiguring frame relaydevices 104A and 104B (via local console/terminals 106A, 106B,respectively), and also may include reconfiguring the appropriateswitches 108 and/or other devices which are part of FR cloud. Thismanually implemented, time consuming procedure is extremely undesirable.

Additionally, it should be noted that parameters in conventional framerelay network devices are typically derived from a static on-boardconfiguration having minimal interaction with the provisioning switchingdevice in the network and no interaction with the far end device thatterminates the circuit. The presence of various network elements in thenetwork implies that no network element is an isolated entity, butrather is affected by other network elements that surround it.Accordingly, control actions performed on one network element can affectother network elements. Since the performance of the “switching fabric”can affect the performance of the “edge devices”, it is preferable toprovide a network model which is able to accommodate the“multi-variable” nature of networks and implement a control schemewherein information from at least a portion of related network elementsis collected before a management or control decision is made at aparticular network element.

Using the technique of the present invention, a dynamic feedback-basedadaptive network may be provided for automatically detecting a client'sneed for increased bandwidth, and for automatically and dynamicallyreconfiguring the appropriate network elements to provide sufficientbandwidth on the virtual circuit to support the user's currentapplication(s). The feedback-based adaptive network of the presentinvention monitors current conditions of local and/or remote networkelements and dynamically adjusts network control parameters based uponanalysis of the monitored network elements. A specific embodiment of thedynamically configurable feedback-based adaptive network of the presentinvention is shown in FIG. 2 of the drawings.

The feedback-based adaptive network of the present invention utilizes atechnique wherein at least a portion of the network elements (e.g.,204A, 204B, 208A, 208B, etc.) report network information relating tonetwork conditions to a centralized data storage entity (e.g., datastore 252). The reported data corresponds to information relating to thecurrent condition or status of each of the reporting network elements inthe network. The information which is reported to the data store 252 isanalyzed by a policy engine 254. The policy engine 254 includes aplurality of application specific plug-in policies for analyzingapplication specific information from the data store and for computingupdated control information based upon the analysis of the information.The updated control information may include any type of information,parameters, and/or actions which may be used to affect the operation ofone or more network elements. The updated control information is thenfed back to selected network elements to thereby affect operation of theselected elements and/or network. Typically, when the operation of anetwork element has been affected, its corresponding operatingparameters and/or operating information will change. The changedoperating parameters are then reported to the data store 252 andanalyzed by the policy engine 254. The policy engine may then generatenew or updated control information or parameters for affecting theoperation of selected elements in the network. In this way, the networkof FIG. 2 is configured to adapt to changing conditions in the networkby providing a dynamic feedback mechanism. Using this dynamic feedbackmechanism, selected network elements may be dynamically andautomatically reconfigured to cause the performance of various aspectsof the network to conform with desired performance criteria.

The feedback-based adaptive network of FIG. 2 includes a plurality ofnetwork elements 204A, 208A, 208B, 204B, which are part of thecommunication path between user 202 and user 214. In the embodiment ofFIG. 2, each of the network elements 204A and 204B may be, for example,a server or a router which communicate with each other via a wide areanetwork (WAN) 210. The WAN may include a plurality of network elements(NE) 208A, 208B, which may include switches and/or other networkelements for providing a communication link between element 204A and204B.

It will be appreciated, however, that the dynamic feedback-basedadaptive network technique of the present invention may be implementedin any conventional data network for providing adaptive and automaticfeedback control of network elements within that network. Thus, forexample, the technique of the present invention may be implemented inconventional LANs, WANs, MANs, internetworks, general purpose networks,packet switched networks, circuit switched networks, etc. Moreover, thetechnique of the present invention may be applied to any conventionaldata network.

As used in this application, the term “control element” refers to theadditional hardware and/or software control components for implementingdynamic feedback control of a conventional network. For example, in theembodiment of FIG. 2, the control elements include data store 252,monitor system 262, ADMIN system 260, policy engine 254, and eventserver 270. Additionally, as used in this application, the term “networkelement” refers to any hardware or software component of the adaptivefeedback-based network of the present invention, including controlelements.

The network element may be a logical or physical entity within thenetwork which is being managed or controlled. The network element ispreferably designed with built-in instrumentation which allows for thecollection of relevant information which may be subsequently used todetermine control actions to be applied to the network element. In thenetwork of FIG. 2, network element 204A may be any hardware or softwarecomponent which has a measurable parameter that can be reported.Examples of network elements include routers, switches, hosts, modems,terminals, dial access servers, gateways, ports, channels, interfaces,circuits, processes, drivers, protocols, services, applications, etc.

In accordance with a specific embodiment, a network element which hasbeen configured to support the feedback-based adaptive configurationtechnique of the present invention will include a monitor/agent (notshown) for monitoring, measuring and/or computing information (e.g.state data) and for reporting this information to the data store 252.The monitor/agent may be implemented via hardware, software, or a hybridcombination of hardware and software. The reported information may beused by the policy engine 254 to calculate updated control informationfor effecting the operation of the network element 204A. As described ingreater detail below, there are a number of ways in which the updatedcontrol information may be fed back into the network element. Oncereceived, the network element will automatically configure itselfutilizing the updated control information to thereby affect itsoperation, which may include affecting one or more operationalparameters of the network elements.

In a specific embodiment where the network element is part of a framerelay circuit, examples of the information reported by the networkelement may include information relating to: committed information rate(CIR), excess information rate (EIR), committed burst size (Bc), excessburst size (Be), congestion indicators (e.g., discarded eligibilitybits), number of packets dropped (e.g. during a given time interval),queue length at selected circuits within the network element, etc.Further, any of the above described parameters may be dynamically andautomatically modified or updated by the policy engine and fed back todesired network elements for affecting the operation or performance ofthe network.

According to the embodiment of FIG. 2, each network element whichreports its respective operating information to data store 252, such as,for example network element 204A, includes a local cache 276A and anevent handler (EH) 274A for handling event notification/registration.Cache 276A represents any type of memory device which may be used forstoring and/or caching updated control information received at thenetwork element. In a specific embodiment, this memory device may be apersistent store. After the updated control information has been cachedinto local cache 276A, the network element retrieves the updated controlinformation from the cache and re-configures itself using this updatedcontrol information. Additionally, as shown in FIG. 2, network elements208A and 208B may also include respective local caches (C) 276A, 276Bfor storing updated control information, and may also include respectiveevent handling entities (EH) for receiving/reporting event notificationinformation.

Although many of the various features of the present invention aredescribed with respect to the network element 204A of FIG. 2, it will beappreciated that the descriptions of the various techniques of thepresent invention are applicable to any network element in the network.However, for purposes of simplification, network element 204A is used inthis application to exemplify many of the techniques provided by thepresent invention.

One advantage of providing a local cache 276A for storing updatedcontrol information is that this data will be available for use by thenetwork element even during times when the communication link betweenthe network element and other parts of the network (e.g., data store252, event server 270, policy engine 254, etc.) have been interrupted.Thus, for example, when the network element is unable to accessinformation from the data store or other network elements, the localcache 276A may be accessed in place of data store 252. In specificembodiments where the protocol for accessing data within data store 252differs from the protocol for accessing data within data cache 276A, atranslation mechanism may be provided. For example, where the data storeis implemented as an LDAP server, and the local cache is implemented asa file system, a translation mechanism will be provided at the networkelement for converting LDAP calls into file system calls and vice versa.

In a specific embodiment, all current control parameters used by aparticular network element (e.g. network element 204A) are maintainedwithin its local cache 276A. The network element configures itself usingthe control information contained within the local cache 276A.Periodically, when the control information for that network element isupdated (by policy engine 254, for example), the updated controlinformation is then stored within cache 276A. Thereafter, the networkelement may reconfigure itself using the updated control informationstored within cache 276A. This feature is described in greater detail ina latter section of this application relating to FIGS. 9B and 10 of thedrawings. In at least one embodiment, the cache is implemented usingnon-volatile memory so that the updated control information may be savedin the event of a power failure of the network element.

One advantage of caching the updated control information within cache276A is that the updated control information may be immediately storedwithin cache 276A even during times when the network element itself isbusy and unable to immediately reconfigure itself using the updatedcontrol information. In this way, the device which handles the datatransfer and caching operation is able to complete its task withouthaving to wait for the network element to be available forre-configuration before caching the updated information.

In an alternate embodiment, the current control parameters used by thenetwork element are maintained in a main memory of the network element(not shown). In this embodiment, cache 276A functions primarily as aback-up in case of a connection failure with other parts of the network.The updated control information are pushed directly into the main memoryof the network element and the control action is immediatelyimplemented. Additionally, the updated control information is storedwithin cache 276A, which acts as a default/back-up mechanism. When acommunication failure occurs and the network element is unable to accessthe updated control information from the data store, event server,and/or policy engine, the network element resorts to retrieving controlparameters from the cache 276A.

As shown in FIG. 2, network element 204A includes an event handler 274A.In a specific embodiment, each network element which receives itscontrol information from the data store includes an associated eventnotification agent.

In a specific embodiment, the event notification service is implementedusing a standardized common object request broker architecture (CORBA)event service API, commonly known to those skilled in the art. However,although the standardized CORBA event service API is generally known tothose having ordinary skill in the relevant art, the use of a CORBAevent service as a notification mechanism to notify data networkelements of changed network conditions and/or parameters is believed tobe a novel concept. In an alternate embodiment, the well known simplenetwork management protocol (SNMP) may be used for implementing eventnotification in the feedback-based adaptive network of the presentinvention. Alternatively, event notification may be implemented byutilizing IP sockets.

One purpose of event handler 274A is to provide the ability for networkelement 204A to register with an event server in order to receivenotification for specified events, such as, for example, theavailability of updated control information at data store 252. In aspecific embodiment, event handler 274A may consult a configuration file(residing at element 204A) in order to determine which events toregister with at event server 270. This feature is described in greaterdetail in a latter section of this application relating to FIG. 7 of thedrawings.

Another purpose of event handler 274A is to provide the ability for thenetwork element to receive event notification messages from event server270. Thus, once the event handler has registered for event notificationwith event server 270, the event handler is then able to receive eventnotification messages from event server 270, and take appropriateaction. This feature is described in greater detail in a latter sectionof this application relating to FIGS. 9A and 9B of the drawings.

Yet another purpose of the event handler is to monitor specified networkelements, and report the detection of specified events (e.g. detectederrors) to event server 270. In a specific embodiment, the event handlermay consult a local configuration file to determine the particular typeof events it is to be monitoring at a specified network element. In analternate embodiment, the event handler is statically pre-configured sothat when it is initialized, it automatically monitors a specifiednetwork element for specific types of events and reports detected eventsto event server 270. For example, when an error is detected by networkelement 204A, the event handler 274A will report the error to eventserver 270 to be forwarded to other network and/or control elements(e.g. policy engine 254), which may be interested in this type ofinformation. This feature is described in greater detail in a lattersection of this application relating to FIG. 9B of the drawings.

Although a detailed explanation of the event notification service isprovided in latter sections of this application, a brief example willnow be provided using the network of FIG. 2.

In this example, it will be assumed that network element 204A uses eventhandler 274A to register for event notification service with eventserver 270. When the policy engine 254 calculates updated controlinformation for network element 204A, it stores the updated controlinformation in data store 252. Event handler 272 continually monitorsthe data store for updated control information and other events. In analternate embodiment (not shown) the event handler 272 may physicallyreside at a device other than data store 252. When the event handler 272detects newly updated control information within the data store relatingto network element 204A, it notifies event server 270 which, in turn,notifies network element 204A of the updated control information. In oneembodiment, the actual control information is passed to the networkelement and cached within local cache 276A. In an alternate embodiment,notification relating to the availability of updated control informationis passed to the network element (via event handler 274A). The networkelement then responds to this notification by retrieving the appropriateupdated control information from data store 252 and caching theretrieved data into cache 276A.

It will be appreciated that the above-described event notificationtechnique may be applied to any desired network element within thenetwork. Further, it will be appreciated that any description ofhardware and/or software features relating to a specific network elementof the present invention (such as, for example, element 204A) may alsobe extended to other network elements in the network (e.g., 208A, 208B,204B).

Generally, the dynamic feedback-based adaptive network element of thepresent invention may be implemented using software and/or hardware. Forexample, it can be implemented in an operating system kernel, in aseparate user process, in a library package bound into networkapplications, on a specially constructed machine, or on a networkinterface card. In a specific embodiment of this invention, thetechnique of the present invention is implemented in software such as anoperating system or in an application running on an operating system.

A software or software/hardware hybrid of the feedback-based adaptivenetwork element of this invention is preferably implemented on ageneral-purpose programmable machine selectively activated orreconfigured by a computer program stored in memory. Such programmablemachine may be a network device designed to handle network traffic. Suchnetwork devices typically have multiple network interfaces includingframe relay and ISDN interfaces, for example. Specific examples of suchnetwork devices include routers and switches. For example, the adaptivefeedback-based network of this invention may include speciallyconfigured routers such as specially configured router models 1600,2500, 2600, 3600, 4500, 4700, 7200, 7500, and 12000 available from CiscoSystems, Inc. of San Jose, Calif. A general architecture for some ofthese machines will appear from the description given below. In analternative embodiment, the adaptive feedback-based network may beimplemented via a general-purpose network host machine such as apersonal computer or workstation. Further, the invention may be at leastpartially implemented on a card (e.g., an interface card) for a networkdevice or a general-purpose computing device.

For example, the network element 204A of FIG. 2 may be a router, such asthe router 10 illustrated in FIG. 5A of the drawings. Referring to FIG.5A, a router 10 is shown which may includes a master central processingunit (CPU) 62, interfaces 68, and a bus 15 (e.g., a PCI bus). Whenacting under the control of appropriate software or firmware, the CPU 62is responsible for such router tasks as routing table computations andnetwork management. It may also be responsible for reporting operatinginformation (relating to the router 10) to one or more external devices,retrieving new or updated control information from an external datasource, caching the retrieved control information, receiving eventnotification messages, generating event messages (relating to the statusof router 10), etc. CPU 62 preferably accomplishes all these functionsunder the control of software including an operating system (e.g., theInternetwork Operating System (IOS®) of Cisco Systems, Inc.) and anyappropriate applications software. CPU 62 may include one or moreprocessors 63 such as a processor from the Motorola family ofmicroprocessors or the MIPS family of microprocessors. In an alternativeembodiment, processor 63 is specially designed hardware for controllingthe operations of router 10. In a specific embodiment, a memory 61 (suchas non-volatile RAM and/or ROM) also forms part of CPU 62. However,there are many different ways in which memory could be coupled to thesystem. Memory block 61 may be used for a variety of purposes such as,for example, caching and/or storing data, programming instructions, etc.

The interfaces 68 are typically provided as interface cards (sometimesreferred to as “line cards”). Generally, they control the sending andreceiving of data packets over the network and sometimes support otherperipherals used with the router 10. Among the interfaces that may beprovided are Ethernet interfaces, frame relay interfaces, cableinterfaces, DSL interfaces, token ring interfaces, and the like. Inaddition, various very high-speed interfaces may be provided such asfast Ethernet interfaces, Gigabit Ethernet interfaces, ATM interfaces,HSSI interfaces, POS interfaces, FDDI interfaces and the like.Generally, these interfaces may include ports appropriate forcommunication with the appropriate media. In some cases, they may alsoinclude an independent processor and, in some instances, volatile RAM.The independent processors may control such communications intensivetasks as packet switching, media control and management. By providingseparate processors for the communications intensive tasks, theseinterfaces allow the master microprocessor 62 to efficiently performrouting computations, network diagnostics, security functions, etc.

Although the system shown in FIG. 5A is one specific router of thepresent invention, it is by no means the only router architecture onwhich the present invention can be implemented. For example, anarchitecture having a single processor that handles communications aswell as routing computations, etc. is often used. Further, other typesof interfaces and media could also be used with the router.

Regardless of network device's configuration, it may employ one or morememories or memory modules (such as, for example, memory block 65)configured to store data and/or store program instructions for thegeneral-purpose network operations and other specific functionsdescribed herein. The program instructions may control the operation ofan operating system and/or one or more applications, for example. Thememory or memories may also be configured to store: current and updatedoperating information relating to the operation of the device, eventnotification messages, device configuration information, programinstructions for implementing event notification service, programinstructions for automatically and dynamically re-configuring the deviceusing updated control information, etc.

Because such information and program instructions may be employed toimplement the systems/methods described herein, the present inventionrelates to machine readable media that include program instructions,operating information, etc. for performing various operations describedherein. Examples of machine-readable media include, but are not limitedto, magnetic media such as hard disks, floppy disks, and magnetic tape;optical media such as CD-ROM disks; magneto-optical media such asfloptical disks; and hardware devices that are specially configured tostore and perform program instructions, such as read-only memory devices(ROM) and random access memory (RAM). The invention may also be embodiedin a carrier wave travelling over an appropriate medium such asairwaves, optical lines, electric lines, etc. Examples of programinstructions include both machine code, such as produced by a compiler,and files containing higher level code that may be executed by thecomputer using an interpreter.

Data Store

As depicted in FIG. 2, data store 252 provides memory for storingcurrent network operating information reported from one or more of thenetwork elements. The data store also provides memory for storingupdated network control information generated by the policy engine 254.The data store may exist on a stand alone device which includes its ownCPU, and operating system (e.g. Windows NT), and memory. Alternatively,the data store may reside as a virtual device at any one of the networkelements. In a specific embodiment (not shown) a plurality of data storedevices may be provided in the network. Where multiple data storedevices are provided, the information within each data store may beredundant (e.g. for back-up purposes or to provide rapid access bynetwork elements). Alternatively, specific data stores may serviceselected portions of the networks in which case the information withineach data store may not be redundant.

Each data store may be implemented as a database, a flat file, adirectory, data cache, or other data storage server implemented on topof some type of data storage media. In a specific embodiment, data store252 of FIG. 2 is implemented as a directory server which supports thelight-weight directory access protocol (LDAP). The LDAP protocol iscommonly known to those having ordinary skill in the art.

In a specific embodiment, the data store may be implemented using theMicrosoft Active Directory (by Microsoft Corporation of Redmond, Wash.)or the Novell Directory (by Novell Corporation of Provo, Utah). Onepurpose of the data store in the feedback-control loop is to collect andstore current network operating information for subsequent analysis.Collecting the operating information allows for flexibility in thecontrol mechanism of the feedback-based network.

An example of data store 252 is shown in FIG. 5B of the drawings. Asshown in FIG. 5B, data store 252 includes a CPU 252C (which may beshared with other devices or agents), an event handling entity 252D, anda data storage block 252F having memory for storing network information.Memory block 252A may be used for storing operational informationreported by the various network elements. This information is used bythe policy engine (254, FIG. 2) to calculate updated control informationrelated to the various network elements. The new or updated controlinformation generated by the policy engine will be stored in block 252Bof the data store. The event handler 252D monitors the data stored inblock 252B as part of the event notification service.

Policy Engine

As described above, in one embodiment of the present invention, updatednetwork conditions from the various network elements are constantly fedinto data store 252. The information in the data store powers a policyengine which, in turn, effects changes in the network. When updatednetwork conditions are fed into the data store, it is important that thepolicy engine be notified of the updated network operating information.The policy engine may either repeatedly poll the data store for updatednetwork data, or rely on an event service to be notified that a changein the network conditions has occurred. When alerted to changes innetwork conditions, the policy engine 254 is then triggered to performits application specific tuning function.

The policy engine 254 is a decision-making (logical) component of thefeedback-based adaptive network of the present invention. An example ofa policy engine 254 is illustrated in FIG. 5C of the drawings. As shownin FIG. 5C, the policy engine 254 includes a policy server 254 a, a CPU254 g (which may reside at the policy server or other device), an eventhandling entity 254 f, and a plurality of application specific plug-inpolicies 254 b-e. An application specific policy is decision tree thatallows the policy server to make a decision based upon measuredvariables and conditions. The definition of “policy” varies based uponthe perspective of the user. In the case of management and control ofnetwork elements, a policy is a corrective action which is used torestore the network element to a pre-determined state.

In a specific embodiment, the policy engine may be implemented on astand alone device which includes CPU, an operating system such as, forexample, Solaris (manufactured by Sun Microsystems of Mountain View,Calif.) or Windows NT (manufactured by Microsoft Corporation of Redmond,Wash.), memory, and a storage device such as disk storage for storing apolicy library of plug-in policies. Alternatively, the policy engine maybe implemented as a virtual device which resides on one of the networkelements such as, for example, a router. Additionally, the policy enginemay be implemented with neural networks or with other artificialintelligence technologies.

The overall architecture of the policy engine is such that it allows forapplication specific plug-in policies to be added or deleted from thesystem. The policy server design is made modular so that decision treemodules can be added and deleted at will without disruption to thepolicy engine. Each application specific plug-in policy module (254b-254 e) may be implemented as a plug-in to the policy server 254 a.Application specific policy plug-ins include frame relay policies, ATMpolicies, dial up policies, traffic shaping policies, quality of service(QoS) policies, security policies, admin policies, SLA policies, etc.Examples of various application specific policy plug-ins are shown inFIG. 5C, and include an ATM policy plug-in 254 b, a frame relay policyplug-in 254 b, a dial up policy plug-in 254 b, and a security policyplug-in 254 e. The examples shown in FIG. 5C merely illustrate some ofthe various application specific policy plug-ins which may be attachedto the policy server 254A.

Each application specific plug-in policy module may include one or morepolicies. For example, the frame relay policy plug-in 254 c may includea first policy for controlling the CIR parameter of a frame relaycircuit, and may include a second policy for controlling the EIRparameter of a frame relay circuit. Each policy contains a specific setof rules for analyzing specific information from selected networkelements, and for generating updated control information in response tothe analysis of the gathered information. The policy may includeprotocol specific rules, business logic rules, event notification rules,etc. Further, as described in greater detail below, the policies may bedynamically re-configured during run-time, meaning that a specificpolicy may be dynamically modified in situations, such as, for example,where it is determined that the current policy for controlling an aspectof network performance is ineffective.

In a specific embodiment, the policies which form part of the policyengine may be stored in a policy library. Each policy may be implementedas a decision tree comprised of nodes, wherein at each node an actionmay be performed if specified criteria is satisfied. The policy may beconfigured as an application or program which runs on top of theoperating system of the policy server. The policy engine traverses thedecision trees of the various policies. Policies may be used to monitor,manage, and/or control a variety of network characteristics includingquality of service (QoS), security, access, usage, etc.

Thus, for example, the policy engine may be used to implement policiesat one end of the frame relay link based upon conditions at the otherend of the link. If a link that is downstream from a switching networkexperiences congestion, the policy engine will dynamically control theupstream link to adapt to the network conditions so that the downstreamnetwork does not drop any packets.

FIG. 12 shows an example of a flow diagram representing a CIR policy (ordecision tree) for a frame relay network. The frame relay CIR analysispolicy 1200 is responsible for analyzing CIR information reported to thedata store, and for generating updated CIR values based upon theanalysis of the reported information. The updated CIR data may then beused by various elements in the network to modify or affect eachelement's respective behavior or operation (thereby affecting operationof the network). In this way, the network elements are able toautomatically and dynamically adapt to changing network conditions.

In a specific embodiment, each block within the flow diagram of FIG. 12represents one or more nodes in a policy tree of the frame relay CIRpolicy 1200. The policy 1200 of FIG. 12 may be traversed by a policyserver which has been configured to analyze each node in the policy treeand take appropriate action in response to the analysis. An example of apolicy analysis procedure is shown in FIG. 11 of the drawings.

FIG. 11 shows an example of a flow diagram of a policy analysisprocedure 1100 which may be used for traversing nodes in a policy treesuch as the policy tree described in FIG. 12. At 1102, a specificapplication policy is loaded into the policy server for execution. Theapplication specific policy may be automatically loaded upon oninitialization of the policy analysis procedure, or may be loadedsubsequently upon the occurrence of an event, such as, for example, theexecution of a specific user application. In a specific embodiment, thepolicy analysis procedure 1100 is a multiple threaded process with eachthread running its own application specific policy. Alternatively, thepolicy analysis procedure 1100 may be implemented as multiple processesor as a single threaded process with multiple concurrent runtimeinstances. It will be appreciated that either of these embodimentsallows for multiple policy processes to be running concurrently in orderto dynamically control various aspects of the network performance.

Starting at the top of policy tree (1104), the current node in thepolicy tree is read (1106). If the current node is a read node (1108),then the policy server performs the specified read operation (1120). Ifthe current node is a write node (1110), the policy server performs thespecified write operation (1122). If the current node is a script node(1112), the policy server runs the specified script (1124). A scriptnode may be composed of multiple read nodes, write nodes, state nodes,computation nodes, etc. Script nodes compute the next state in thepolicy tree based upon the results of the computation. If the currentnode is a compute node (1114), the policy server performs the specifiedcomputation (1126). If the current node is a state node (1116), thepolicy server branches to the appropriate node in the policy tree(1128). If the format or instructions at the current node are notrecognized, an error is returned and the policy tree is exited (1118).Moreover, where an error occurs, the processing of the policy isaborted.

After the policy analysis procedure has performed the appropriate actionin accordance with the current node in the policy tree, a determinationis made as to whether the current node is the last node in the policytree (1130). If the current node is not the last node in the policytree, the policy analysis procedure proceeds (1132) to the next node inthe policy tree, whereupon the next node is processed as described above(e.g. starting at block 1106).

If, however, the current node in the policy tree is the last node in thepolicy tree, at 1134, a determination is made as to whether the policyanalysis procedure should be repeated for the currently loaded policy.In some instances, it may be desirable to have specific policiescontinuously running in order to provide continuous monitoring and/orupdating of network parameters. In other instances, it may be desirableto have a specific policy procedure analysis concurrently running onlywhile a specific user application is running.

If it is determined that the policy analysis procedure is not to berepeated for the currently loaded policy, the policy analysis procedureis exited. However, if it is determined that the policy analysisprocedure is to be repeated for the currently loaded policy, at 1136, adetermination is made as to whether the current policy has been modifiedby other control elements in the network. As described in greater detailin a latter section of this application, a policy within policy engine254 may be dynamically modified in order to alter the way in which thatpolicy effects control of the network. In a specific embodiment, forexample, when a specific policy has been modified, an associatedregister or flag may be set. At block 1136, this flag or register may bechecked to determine if the code for the currently loaded policy hasbeen modified. If it is determined that the currently loaded policy hasbeen or is about to be modified, the modified policy is then loaded(1102) and executed by the policy server. If, however, it is determinedthat the currently loaded policy has not been or is not about to bemodified, the policy analysis procedure returns to the top node in thepolicy tree (1104) and repeats the analysis procedure of the currentpolicy as described above.

By way of example, the policy analysis procedure 1100 of FIG. 11 willnow be applied to the frame relay CIR policy tree of FIG. 12. The framerelay CIR policy analysis procedure of FIG. 12 may be used, for example,to provide updated CIR parameter data to frame relay network elements304A and 304B of FIG. 3 based upon the number of packets dropped onlinks B and C of FIG. 3. Using the technique of the present invention,adaptive frame relay parameter handling can be expanded to supportcomplex situations without operator intervention.

Referring to FIG. 12, at 1201, the frame relay CIR policy is loaded bythe policy analysis procedure 1100. After the frame relay CIR policy hasbeen loaded by the policy server, at 1202, various parameters areinitialized. The values used for parameter initialization may bederived, for example, from a configuration file associated with theframe relay CIR policy. The specific parameters initialized in box 1202describe a threshold value (representing a maximum allowable value ofdropped packets for a given link), a data source for retrieving networkelement information and for writing updated control information (e.g.,data store, network element), and specific formulae used for computingupdated CIR values based upon the number of packets dropped from aparticular link.

After the initialization parameters have been set, at 1204, the packetdropped count data for link B is retrieved from the specified datasource and assigned to the variable X. In a specific embodiment, thespecified data source is data store 352. In an alternate embodiment, thespecified data source may be network element 304A. However, for purposesof this example, it will be assumed that the data source is data store352. Next, the dropped packet count for link C is read (1206) from thedata store and assigned to the variable Y.

At 1208, the dropped packet count values from links B and C are eachcompared with the threshold dropped packet count value (set duringinitialization at 1202). If the dropped packet count value for either oflinks B or C do not exceed the established threshold value, then it maybe inferred that the current CIR values for links B and C are adequatefor achieving a desired network performance which conforms withpredetermined criteria or specified guidelines. In the example of FIG.12, network performance is determined using predetermined criteria whichis related to the threshold value of the dropped packet count for linksB and C. Thus, if the dropped packet counts for links B and C conformwith (i.e., are less than or equal) the predetermined criteria specifiedby the threshold dropped packet count value, that particular aspect ofnetwork performance is determined to be adequate. Accordingly, theexisting CIR values for links B and C need not be modified or updated atthe present time. The CIR analysis then continues at block 1218 whereinthe frame relay CIR policy procedure waits (1218) a predetermined timeinterval (T) (e.g. 5 sec.-30 sec.) before either repeating the procedure(1220) or exiting the procedure (1224).

If either of the dropped packet count values from links B or C exceedsthe threshold dropped packet count value, it may be inferred that atleast one of the CIR values for links B and/or C is inadequate formaintaining a dropped packet count for each of the links below thethreshold value. Accordingly, in order to adapt to this change in thenetwork conditions, the CIR values for links B and C are recomputed.

In order to re-compute the CIR values for links B and C, the current CIRvalues for these links are retrieved (1210) from either the data storeor directly from the appropriate network elements. Next, the CIR valuefor link B is recomputed (1212) based upon a specified formula which maybe provided by, for example, a configuration file related to the framerelay CIR policy. Similarly, at 1214, the CIR value for link C isrecomputed based upon the specified formula.

An example of one formula which may be used for computing updated CIRvalues is:New CIR value=old CIR value*(1+N)*K,where fraction

${N = \frac{{Dropped\_ Bits}/{Sec}}{CIR}},{0 < N < 1},\mspace{14mu}{{and}\mspace{14mu} K}$is a predetermined constant (e.g. K=1) which may be dynamically adjustedto alter the ratio between the old CIR value and the new CIR value for aspecified link. As explained in greater detail in a latter section ofthis application, each policy within the policy engine may bedynamically modified upon determining that the current policy procedureis ineffective in controlling an aspect of the network performance toconform with predetermined guidelines or criteria. Thus, in the exampleof FIG. 12, if it is determined that current formula used forre-computing the CIR values is ineffective in reducing the droppedpacket count for links B and C, the formula may be dynamically andautomatically altered, for example, by changing the value of thevariable K.

Once the updated CIR parameter values for links B and C have beencomputed (at 1212 and 1214), the updated CIR parameter values are thenwritten (1216) into the data store 352. The frame relay CIR policyprocedure then waits (1218) a predetermined time interval (e.g. 0-30minutes) before either repeating the procedure or exiting the procedure.

After the predetermined time interval has elapsed, a determination ismade as to whether the frame relay CIR policy procedure 1200 is to berepeated. This determination may be implemented using a variety ofcommonly known techniques, for example, by consulting a specific statusflag, by polling, by receiving instructions from an external source,etc. If it is determined that the CIR policy procedure is to berepeated, at 1222, a determination is made as to whether the policy hasbeen modified. In a specific embodiment, this determination is made byconsulting a policy modification flag associated with the frame relayCIR policy. If, it is determined that the policy has not been modified,then the CIR policy procedure 1200 resumes at block 1204.

However, if it is determined that the policy has been modified, theprocedure resumes starting at block 1201, whereupon the modified policyis loaded for execution. Additionally, the policy modification flag maybe reset at this time. For example, if the formula for re-computing theCIR values has been modified at any time during execution of the CIRpolicy 1200, a policy modification flag would be set to indicate thatthe policy has been modified. Thereafter, if the CIR policy is repeatedor subsequently executed, the modified formula will be loaded atinitialization and will be used for computing the new CIR values for theappropriate links.

FIG. 4 shows an alternate embodiment of the feedback-based adaptivenetwork of the present invention. The network of FIG. 4 utilizes many ofthe novel concepts described above with respect to FIGS. 2 and 3.However, one difference in the embodiment of the FIG. 4 is that theparticipating network elements (e.g., 404A, 404B, 408A, 408B) receivedtheir respective updated control information directly from the policyengine 454. Thus, for example, in one embodiment, the policy engine 454directly controls each of the network elements by providing updatedcontrol information directly to the network elements. The policy enginemay cache the updated control information into a local data cache (e.g.276A) at a network element. The network element may then retrieve theupdated control information from its local cache and reconfigure itselfusing the retrieved updated control information. Alternatively, thepolicy engine may send a notification signal to selected networkelements, advising each element that updated control information isavailable for that respective element. The network element may thenretrieve the appropriate updated control information from the policyengine 454.

FIGS. 6-10 illustrate examples of flow diagrams relating to variousprocedures associated with the adaptive feedback-based networkillustrated in FIG. 2 of the drawings.

FIG. 6 shows a specific embodiment of a flow diagram for aninitialization procedure 600 of the present invention. Theinitialization procedure 600 may commence by initializing the variousnetwork control elements (602). As stated previously, the term “controlelement” refers to the additional hardware and/or software controlcomponents for implementing dynamic feedback control of a conventionalnetwork, which may include, for example, event server 270, policy engine254, ADMIN system 260, monitor system 262, data store 252, etc.Additionally, the term “network element” refers to any hardware orsoftware component of the adaptive feedback-based network of the presentinvention, including the control elements. At 604, the remaining (i.e.non-control) elements of the network are initialized. In a specificembodiment, each element may be initialized using existing controlparameters which reside in a local cache (e.g., 276A) or a configurationfile (not shown) residing at the network element. Event registration isthen initiated (606) for the various network elements (including networkcontrol elements) via the event handler associated with each element.The event registration procedure is described in greater detail withrespect to FIG. 7.

FIG. 7 shows a flow diagram of an event registration procedure 700 inaccordance with a specific embodiment of the present invention. Eventregistration for a particular network element may be implemented via itsassociated event handler. In the example of FIG. 7, it is assumed thatthe event registration procedure 700 is being implemented at networkelement 204A of FIG. 2.

According to a specific embodiment, the event handler 274A may initiallyconsult a local configuration file (not shown) in order to determinewhich events the network element is to register for at the event server270. The configuration file may be programmed using a command lineinterface terminal 206A. Alternatively, the event handler may bestatically pre-configured to automatically register for specified eventsupon initialization. Thus, at 702, the event handler 274A determines theparticular events for which network element 204A is to be registered atthe event server 270. Thereafter, the event handler 274A registers (704)network element 204A for notification of selected events, for example,by attaching to selected event channels at event server 270. Asdescribed previously, in a specific embodiment the event notificationservice is implemented utilizing a standardized CORBA event service API,commonly known to those skilled in the art. After the network elementhas registered with the event server for event notification, the networkelement is then ready to receive and react to event notificationmessages. Additionally the network element is able to report eventoccurrences (e.g. errors detected by the network element) to the eventserver 270, where other network elements have registered to be notifiedof such events.

FIG. 8 shows a flow diagram of a network element reporting procedure 800in accordance with a specific embodiment of the present invention. Thenetwork element reporting procedure may be initiated, for example,during initialization of the network element. As described in greaterdetail below, the network element reporting procedure 800 is executed atthe network element and provides a technique for causing the networkelement to report specified information of the network element to thedata store.

When the network element reporting procedure 800 is implemented by aspecific network element, the network element first determines (802) theappropriate data store(s) for reporting its operating information. Inone embodiment, the network element may determine the appropriate datastores for reporting its operating information by consulting aconfiguration file residing at the network element. In a specificembodiment, an automated approach using a multicast mechanism fordiscovering the appropriate data stores may be implemented viaadditional software. The automated approach using multicast automatesthe data store selection process and may therefore be independent of theparticular implementation of each data store.

Once the appropriate data store(s) has been identified, the networkelement is then initialized (804) to communicate with the identifieddata store(s). In a specific embodiment where the data store isimplemented as an LDAP directory service, a network element may beinitialized to communicate with the data store utilizing LDAP functioncalls. The LDAP function calls are part of a standard API library whichmay be stored at the network element and used for communicating with theLDAP directory server. In at least one embodiment of the presentinvention, the initialization of the network element to communicate witha data store includes performing a log-on procedure so that the networkelement is logged onto the specified data store(s). If the networkelement is unable to access (806) the identified data store, it willreport (808) the error to event server 270, wait (809) a specified timeperiod (e.g. 0-30 minutes), and then reattempt to communicate (804) withthe identified data store(s).

Once a communication link has been established between the networkelement and the identified data store(s), the network element computesand/or retrieves (807) specific information for reporting to theidentified data store(s). For example, as shown in FIG. 3 various framerelay virtual circuit parameter values (e.g., CIR, EIR, dropped packets,etc.) associated with network element 304A are obtained and reported todata store 352.

In a specific embodiment, the type of operating information which thenetwork element is to report is specified in a configuration filelocated at the network element. This configuration file may bedynamically modified using the feedback technique of the presentinvention in a similar manner by which the control parameters of thenetwork element are dynamically modified. In an alternate embodiment,the network element is hard coded to automatically report specifiedinformation to the data store upon initialization. Moreover, it will beappreciated that the technique of the present invention may be used todynamically modify any file, state, parameter, etc. of any networkelement in the network.

After the specified operating information has been retrieved and/orcomputed by the network element, the network element attempts to access(810) the identified data store(s) for reporting the information. If anyone of the data stores is inaccessible, the network element reports theerror (808) to the event server 270 via its respective event handler,and wait (809) a specified time period (e.g. 0-30 minutes) beforere-attempting to access the data store. It is to be noted that thenetwork element reporting procedure 800 may be implemented as amulti-thread process whereby each thread is used to report networkelement operating information to a respective data store, or wherebyeach thread is used to report a specific portion of operatinginformation to a specified data store. Alternatively, the networkelement reporting procedure 800 may be implemented as multiple processesor as a single threaded process with multiple concurrent runtimeinstances. If one data store is inaccessible while another data store isaccessible by the network element, each runtime instance or thread ofprocedure 800 may take different action as appropriate.

If the network element is able to access a specified data store, thenetwork element reports (814) its data or operating information to thatdata store, whereupon the information is stored at the data store. Inthe specific embodiment where the data store is implemented as an LDAPserver, updated operating information provided by the network elementmay be stored in the data store by using an LDAP library call.

The network element then waits (816) a specified time period beforere-computing and/or retrieving updated operating information to bereported to the data store(s). For example, in a specific embodiment ofthe present invention, the specified time period T (which may bereferred to as a polling interval) may range from 0-30 minutes. However,it will be appreciated that the length of the polling interval may varygreatly and may be appropriately determined based upon the particularnetwork in which the technique of the present invention is implemented.

In at least one embodiment of the present invention, the network elementcontinually reports updated operating information to the data store 252.In the event where the network element is unable to access the datastore, the error will be reported to the event server which, in turn,will notify the appropriate control elements of the error so that thecontrol elements may take appropriate action.

Event Notification Service

According to a specific embodiment of the present invention, theadaptive network relies on a policy engine that uses real-time networkdata (e.g. state data) to make policy decisions for generating updatednetwork control parameters to thereby effect changes in the network.Where the network data to be analyzed is obtained from the data store,it is important that the data in the data store be up-to-date at alltimes. In order for the data to be up-to-date, a notification scheme isprovided both from the network element(s) to the data store, and fromthe data store to the network element(s).

As illustrated in FIG. 2, at least a portion of the network elementsinclude an associated event handling entity or event handler whichcommunicates with event server 270. The event handler may be implementvia software, hardware, or a hybrid combination of software and hardwareand is configured to function as both an event notification receivingentity and an event notification supplying entity for its associatednetwork element (host device). More specifically, the event handlerenables its host device to receive event notification messages relatingto the occurrence of one or more events for which the host device hasregistered to receive notification. Additionally, the event handler isable to provide notification of events related to its host device to theevent server. The event server may then broadcast notice of the event toother event handling entities which have subscribed or registered toreceive event notification messages relating to that particular eventtype. When an event notification message is distributed to any one ofthe network or control elements, it is received by the respective eventhandler of that element. In a specific embodiment, event notificationservice may be implemented utilizing an asynchronous notificationscheme.

Thus, for example, event handler 272 which is associated with data store252 may monitor the availability of updated control information at datastore 252, and notify the event server 270 of the availability of suchdata as it becomes available. The event server 270 may then send eventnotification messages to selected network elements which have registeredto receive event notification relating to the particular updated controlinformation which has become available at data store 252. Using networkelement 204A as an example, the event notification message dispatched byevent server 270 will be received by event handler 274A. In a specificembodiment, the event handler queues and processes each received eventnotification message. During processing of the event notificationmessage, the event handler notifies the network element 204A of theevent occurrence, whereupon the network element may then takeappropriate action. In this way, the event handler 274A serves as anevent notification receiving device.

In addition to serving as an event notification receiving device, theevent handler 274A may also function as an event notification supplyingdevice to the event server 270. For example, if the communication linkbetween the network element 204A and data store 252 is down, the eventhandler 274A may send a message to the event server stating that networkelement 204A is unable to communicate with data store 252. This messagemay, in turn, be distributed to various other components of the systemor network which have subscribed to receive notification of this type ofevent occurrence. For example, ADMIN system 260 may be notified in orderto inform a network administrator of the problem. Additionally, whereappropriate, the ADMIN system 260 may also inform users 202 and/or user214 of the problem. Further, the event server may also notify the policyengine 254 and monitor device 262 of the problem. One reason forinforming policy engine 254 and monitor device 262 of this type ofproblem is to prevent these systems from using erroneous data at datastore 252 to perform feedback control of the various network elements.Thus, for example, if network element 204A is unable to report itscurrent information to data store 252, the policy engine 254 shouldpreferably be notified in order to prevent it from using erroneous orout-dated data (relating to network element 204A) in calculating newcontrol information for the network elements. The same reasoning alsoapplies to monitor device 262. If the information within the data storeis not current or up to date, it is desirable that the policy engine andmonitor device be notified in order to prevent these devices from usingthe outdated or non-current data to dynamically perform feedback controlof various network parameters.

In a specific embodiment of the present invention, each network elementwhich is configured to receive event notification messages uses an eventnotification response procedure for receiving and reacting to the eventnotification message. The event notification response procedure may beconfigured as a multi-thread process which is described, for example, inFIGS. 9A and 9B of the drawings. Alternatively, the event notificationresponse procedure may be implemented as multiple processes or as asingle threaded process with multiple concurrent runtime instances.

FIGS. 9A and 9B illustrate a specific embodiment for implementing amulti-thread process of an event notification response procedure.Referring first to the Event Notification Procedure 900A of FIG. 9A, andusing network element 204A as an example, event handler 274A continuallymonitors (902) selected event notification channels at the event serverto which that network element has attached. When an event notificationmessage is received (902) at the network element, the event handler thenqueues (904) the notification message in a notification queue. Althoughnot specifically shown in FIG. 2, each network element which isconfigured to receive event notification messages includes an eventnotification queue or other data structure for temporarily storing theevent notification messages until that message can be processed

FIG. 9B illustrates a specific embodiment of an Event NotificationResponse Procedure 900B of the present invention. The event notificationresponse procedure 900B is implemented by the network element whichworks in conjunction with the event handling entity of that element forresponding to the event notification message. At 912, the eventnotification queue is checked for any event notification messages whichmay have been enqueued during the procedure of 900A. Assuming there isat least one event notification message in the queue, the oldest eventnotification message is dequeued (913) from the queue and analyzed.Based on the event notification message, specific information relatingto the event is determined (914). For example, where the eventnotification message relates to updated control information beingavailable at data store 252, at 914, the specific control parameterswhich have been updated are determined from the event notificationmessage.

The network element then attempts to access (916) the data store 252 inorder to retrieve the specified updated control information. In theevent that the network element is unable to access the data store, theevent notification message is enqueued (917) in the message notificationqueue, and the error is reported (916) to the event server via thenetwork element event handler. Thereafter, flow of the procedure resumesat 912, whereupon another attempt is made to fully respond to the eventnotification message. In a specific embodiment, any event notificationmessages which have been re-queued (because, for example, they were notable to be fully processed) are processed ahead of other eventnotification messages in the queue. For example, in a specificimplementation, the event notification messages are enqueued in orderaccording to each message's respective arrival time at the networkelement.

It is to be noted that the error reported to the event server 270(relating to the network element not being able to access the datastore) is forwarded for broadcast to any network elements which haveregistered to receive notification of such events. For example, theerror may be reported to the administration system 260 in order to alerta system administrator of the problem. Additionally, the error may bereported to the policy engine 254 in order to inform the policy enginethat network element 204A is no longer reporting current information tothe data store. In this way, the policy engine is prevented fromgenerating new control information based upon erroneous or outdated datalocated at data store 252.

Assuming, however, that the network element is able to access data store252, at 918 the network element retrieves the specified updated controlinformation from data store 252. Any suitable mechanism may be used toretrieve the new values of the updated control information from the datastore. In a specific example where the data store is implemented as anLDAP directory server, an LDAP library call may be used to retrieve theupdated control information. Where the data store is implemented as arelational database, an SQL search command may be used for retrievingthe updated control information. Alternatively, where the data store isimplemented as a file, a read command may be used to retrieve thecontrol information. Where the data store is accessible using a simplenetwork management protocol (SNMP), a get-parameter command may be usedfor retrieving the updated control information.

Once the updated control information has been retrieved from the datastore, the data is validated (920) as a safety precaution in order toensure that the updated control parameter values are within an allowablerange or boundary specific to that particular network element. In aspecific embodiment, the predetermined range or boundary criteria may bestored, for example, in a configuration file residing at the networkelement. In an alternate embodiment, the updated parameter dataretrieved from the data store is dynamically validated based upon aplatform evaluation performed by the network element. For example, thenetwork element may execute a procedure for dynamically determiningupper and lower bounds for a respective control parameters based uponits current operating condition and/or performance. The upper and lowerbounds for these parameters may then be used to validate the controlinformation retrieved from the data store. If the retrieved values fromthe data store are determined to be invalid, the network element maysimply ignore the updated parameter data and continue to behave usingits current control parameter information. Additionally, where thevalues in the data store are determined to be invalid, the networkelement may report the error or problem to the event server 270, whichmay then forward the error information to other appropriate controlelements for logging or responding to the error.

Thus, at 922, a determination is made as to whether the retrievedupdated control information is valid based upon the validation preformedat block 920. If the retrieved parameter data is not valid, the valuesare discarded and an error is reported (925) to the event server 270 fordistribution to appropriate network elements. Thereafter, flow controlof the procedure 900B resumes at block 912. If, however, it isdetermined that the retrieved parameter data is valid, at 924 the newlyretrieved control information is written in to the local cache or memory276A of the network element. In a specific implementation, a “cacheddata” flag or register is set to indicate that new or updated controlinformation exist within the local cache 276A. Thereafter, flow controlof the procedure returns to block 912.

In alternate embodiments of the present invention the event responseprocedure 900B may differ slightly depending upon how the adaptivefeedback-based network of the present invention is implemented. Forexample, in a specific alternate embodiment, the actual values relatingto the updated control information are passed in the event notificationmessage to the corresponding network element. Thus, in this embodiment,the actual values relating to the updated control information may bedetermined directly from the event notification message upon dequeuingthe message from the notification queue. Accordingly, the networkelement need not retrieve the updated control information from the datastore.

After new or updated control information has been cached into the localcache of a respective network element, a network element parameterupdate procedure is used to configure or reconfigure the network elementusing the updated control information cached within the local cache.

FIG. 10 shows a network element parameter update procedure 1000 inaccordance with a specific embodiment of the present invention.Procedure 1000 may be implemented automatically by the network elementupon determining that updated control information is available in itslocal cache. Initially, at 1002, the procedure waits until it isnotified that new data has been cached into the local cache. In aspecific embodiment this is implemented via a “cached data” register orflag. However, it will be appreciated by those having ordinary skill inthe art that there are a variety of conventional techniques fordetermining whether new data has been cached into the local cache of thenetwork element.

If it is determined that new data has been written in to the local cache276A, the newly cached data is retrieved (1004). The network elementthen automatically configures or reconfigures itself (1006) using thecached information. The cached information represents updated controlinformation generated by the policy engine in response to changingnetwork conditions. Typically, when the network element configuresitself using the updated control information, its performance and/oroperation is affected in some manner. This effect of the performance oroperation of the network element will typically be reflected in the newoperational information which the network element reports to data store252. This new information will, in turn, be analyzed by the policyengine 254, which may generate new control information in response tothe newly reported information from the network element. In this way,feedback control of the network element is achieved.

After the network element has been reconfigured utilizing the updatedcontrol information, the “cached data” flag or other indicator used forindicating new data cached within the local cache 276A may be reset.Thereafter, the process returns to a previous state represented by block1002.

As described previously, the adaptive feedback-based network of thepresent invention includes an event notification service which isimplemented via event server 270 and the plurality of event handlersassociated with the network and control elements. Event server 270 (FIG.2) may be implemented as a separate device having at least one CPU andmemory, or, alternatively, can be implemented as an application to runon top of the operating system of another device in the network. Oneresponsibility of the event server is to manage the plurality of eventchannels which are used by the various event handling entities totransmit and receive event notification messages. When an event handlerdetects an occurrence of an event, the event handler reports the eventto the event server 270 which, in turn, broadcasts an event notificationmessage to selected network elements using a specific event channel. Ina specific embodiment of the present invention, the event notificationservice is implemented using standardized CORBA event service APIs.

FIG. 15 shows an example of a flow diagram for a data store eventhandler reporting procedure 1500, in accordance with a specificembodiment of the present invention. Procedure 1500 may be implementedvia the event handling entity 272 residing at data store 252. Oneresponsibility of event handler 272 is to continually monitor the datastore for new or updated control information which has been generated bythe network elements or by the policy engine 254. When event handler 272detects the occurrence or availability of a new control parameter, itnotifies the event server 270 which distributes the event notificationmessage onto the appropriate network element(s). In a specificembodiment, event handler 272 may be implemented as a process withmultiple threads. Each thread may be responsible for monitoring andreporting a specific event occurring at data store 252. Alternatively,event handler 272 may be implemented as a single threaded process whichallows for multiple runtime instances to be running concurrently. Forexample, one thread or runtime instance of event handler 272 maycontinually monitor the data store for updated CIR data associated witha first subset of network elements in the network. A different thread orruntime instance of event handler 272 may continually monitor the datastore for updated EIR parameters associated with a second subset ofnetwork elements. Thus, it will be appreciated that the data store eventhandler reporting procedure 1500 describes a monitoring and reportingtechnique which may be implemented by one of the multiple threads orrun-time instances of event handler 272.

Referring to FIG. 15, upon initialization of the event handler 272, orat some point thereafter, the event handler determines (1502) theparticular event(s) to be monitored for reporting to event server 270.In a specific embodiment, this information may be determined byconsulting a configuration file associated with data store 252.Alternatively, the event handler may be hard coded to automaticallymonitor specified events upon initialization. Additionally, once thespecific event(s) to be monitored have been identified, the eventhandler determines the associated event channel(s) for attachment (tothe event server) relating to the identified event(s) to be monitored.

Once the event handler has determined the specific event channels forattachment, it attaches (1504) to the specified event channels at eventserver 270. In a specific embodiment, the event handler may attachitself to the specified event channels at the event server usingstandardized CORBA APIs. Thereafter, at 1506, the event handlerprocedure opens a connection with the data store 252. In a specificembodiment, the connection with the data store is established using aJava naming and directory interface (JNDI).

After a connection with the data store has been established, the eventhandler is then able to retrieve specific data from the data store inorder to determine whether the specified data has been updated by thepolicy engine. In a specific embodiment, the particular data retrievedby the event handler is specified in the event handler programminginstructions. In the example of FIG. 15, it is assumed that the eventhandler is responsible for reporting updated control information storedwithin data store 252. Accordingly, the event handler will retrieve(1508) the current control parameter values reported by the variousnetwork elements to the data store, and will also retrieve (1510) thedesired or updated control parameter values generated by the policyengine. For example, where the specific event relates to updated CIRvalues for the frame relay circuit associated with network element 204A(FIG. 2), the event handler will retrieve the current CIR value reportedfrom network element 204A to the data store, and will also retrieve thedesired CIR value for the frame relay circuit associated with element204A generated by the policy engine. At 1512, the current and desiredcontrol parameter values are compared in order to determine (1514) ifthe values have changed or have been modified by the policy engine.

If it is determined that there is no change between the current anddesired values of the specific control parameter being analyzed, theprocedure waits (1518) a specified time period (e.g., 0-30 minutes)before repeating the analysis, starting at block 1508. In an alternateembodiment, this wait cycle may be replaced by another event serviceroutine.

If, however, it is determined that the current control parameter valuereported from the network element differs from the desired controlparameter values generated by the policy engine, the event handler willgenerate (1516) an event message. In a specific embodiment, this eventchange message may be forwarded to the event server 270 for distributionto other network elements. Thereafter, the event handler will wait aspecified time period before repeating procedure 1500 starting at block1508.

Monitor System and ADMIN system

As described previously, at least one embodiment of the adaptivefeedback-based network of the present invention includes a monitorsystem (262, FIG. 2). As described in greater detail below, monitorsystem 262 may be configured to serve a variety of purposes, andtherefore may be referred to by different names, depending upon theparticular function it is performing. Like the policy engine, themonitor system 262 may be implemented as a separate machine havingmemory, an operating system (e.g. Windows NT, UNIX, LINUX, DOS, etc.),and at least one CPU. Alternatively, monitor system 262 may beimplemented on top of the operating system of another one of the networkelements (including the control elements). In this latter embodiment, itis possible for the monitor system to share the event handler deviceassociated with that network element. In a specific embodiment, themonitor system 262 may be implemented in Java, and run on one of theabove-described platforms. Additionally monitor system 262 may include aplurality of business application plug-ins for analyzing various aspectsof network performance or other network characteristics.

In a specific embodiment, monitor system 262 utilizes the policy engine254 for running the plurality of plug-in applications associated withthe monitor system. Thus, according to one embodiment (not shown),monitor system 262 may be configured to run on top of the policy engine254. In this embodiment, the monitor system may not include a separateevent handler device, but instead may use the event handler deviceassociated with the policy engine.

Each of the business application plug-ins utilized by the monitor system262 may be used to evaluate a specific set of characteristics of thenetwork. For example, monitor system 262 may be used to evaluateperformance criteria of the various network elements to determinewhether the service quality provided by the service provider conformswith the standards set forth in a Service Level Agreement (SLA)established between the service provider and the end user or consumer.Alternatively, using different plug-in applications, monitor system 262may be used for performance monitoring, billing, configurationmanagement, security violation reporting, fault management, etc.Moreover, different plug-in applications may run concurrently to allowmonitor system 262 to analyze different aspects of the networksimultaneously.

FIG. 13 shows a flow diagram of a network performance quality monitorprocedure 1300 in accordance with a specific embodiment of the presentinvention. According to one embodiment, the network performance qualitymonitor procedure is a multi-thread process which is implemented by themonitor system 262. Alternatively, the network performance qualitymonitor procedure may be implemented as a single threaded process whichallows for multiple runtime instances of the process to be runningconcurrently. Accordingly, a variety of different networkcharacteristics may be analyzed concurrently by the monitor system 262.For each thread or runtime instance of the monitoring procedure 1300, aspecific procedure or business application plug-in for analyzing anaspect of network characteristics is loaded (1301) for execution. At1302, various initialization procedures are performed, which may includelocating and attaching to a “data source” for retrieving data which isto be analyzed, determining the specific network parameters which are tobe analyzed, retrieving predetermined network criteria, etc. Theinitialization information may be obtained, for example, by consulting aconfiguration file associated with the particular business applicationplug-in which is loaded. Alternatively, the initialization may beincluded within the program instructions of the loaded plug-inapplication. For example, in a specific embodiment, the data source forretrieving the network parameter information to be analyzed is the datastore which may be accessed, for example, using a directory accessprotocol. The specific information to be analyzed from the data storemay include, for example, reported CIR and EIR values from each of thelinks A, B, C, D, (FIG. 2). The predetermined network criteria mayinclude, for example, specific CIR and EIR values derived from theService Level Agreement.

In a specific embodiment, the network quality monitor system 262includes functionality to gather information from the data store andfunctionality to perform quality metrics calculation process. Block 1304describes the network statistics gathering functionality. Basically,network statistics or other characteristics are gathered or retrievedfrom one or more data sources. It is to be noted that the data sourcemay include any network element or control device within the network. Ina specific embodiment, the network statistics are retrieved from thedata store.

The quality metrics calculation functionality is described in block1306. The network statistics or other characteristics which have beenretrieved from the data store are then compared against pre-establishedcriteria to determine (1308) if the current network quality (relating tothe particular aspect of the network being analyzed) is within theacceptable bounds as established by the predetermined criteria.

If it is determined that the currently analyzed network statistics arewithin the acceptable bounds as defined by the predetermined networkcriteria, the monitor procedure 1300 waits (1312) a specified timeinterval (e.g., 0-30 minutes) before repeating the analysis starting atblock 1304. If, however, it is determined that the current networkstatistics do not meet the specified predetermined criteria, the problemis reported (1310) to the ADMIN system 260 for handling. Thereafter, themonitor procedure 1300 waits (1312) a specified time interval beforerepeating the analysis, starting at block 1304. Further examples of thenetwork quality monitor procedures which may be run by monitor system262 are provided in the descriptions of FIGS. 16-18.

Monitor system 262 and ADMIN system 260 work together to provideadministrative functionality to the adaptive feedback-based network ofthe present invention. Additionally, the administration system 260provides an external interface to remote users, (e.g., users 202, 214,FIG. 2). Using the ADMIN system 260, a remote user is provided with theability to perform configuration and manipulation of the logicalelements within the network. The ADMIN system 260 may be implemented asa separate machine having memory, an operating system (e.g. Windows NT,UNIX, LINUX, DOS, etc.), and at least one CPU. Alternatively, ADMINsystem 262 may be implemented on top of the operating system of anotherone of the network elements (including the control elements).

FIG. 14 shows a flow diagram of an admin procedure 1400 in accordancewith a specific embodiment of the present invention. The admin procedure1400 is implemented by ADMIN system 260, and may be implemented as amulti-thread process. Alternatively, the admin procedure 1400 may beimplemented as a single threaded process which allows for multipleruntime instances of the process to be running concurrently. Asdescribed previously, the ADMIN system 260 may be used to dynamicallymodify specific policies within the policy engine 254.

In one embodiment of the present invention, policies in the control ofWAN services are essentially treated as static entities. However, inalternate embodiments, a mechanism is provided for allowing thesepolicies to adapt to changing network conditions in order to enable thenetwork to adapt to changing network conditions. Networks that adapt tochanging conditions are very advantageous in fulfilling Service LevelAgreements (SLA) in WAN networks. Moreover, a dynamic, policy-enabled,adaptive network can be a self-healing, maintenance-free network.

In a specific embodiment, there are at least three techniques forachieving modification of a policy within the policy engine 254. A firsttechnique is for a remote user to dynamically modify the policy viaADMIN system 260. A second technique is for a system administrator tomodify the policy via local terminal 266. A third technique to enablethe ADMIN system 260 to automatically and dynamically modify a policywithin the policy engine using artificial intelligence and/or fuzzylogic to determine the specific policy modifications. The adminprocedure 1400 of FIG. 14 provides an example of how these varioustechniques are implemented at the ADMIN system 260.

In the specific embodiment of the FIG. 14, admin procedure 1400 isresponsive to either a input from a user (1402) or an input from themonitor system 262 for modifying a policy within the policy engine 254.If input is received from a user, it will be assumed (for purposes ofthis example) that the user has provided a request to make a specificpolicy modification, and has included the specific policy modificationsto be performed along with the request. In this example, a user may beuser 202 of FIG. 2, or may be a system administrator accessing ADMINsystem via local console 266. At 1404, admin procedure 1400 determineswhether the user has permission to modify or change the specifiedpolicy. For example, an access list may be consulted to determine if theuser has authority to make the proposed policy modification. If it isdetermined that the user does not have authority to make the proposedmodification, at 1408, an unauthorized request message is returned tothe user, whereupon the procedure 1400 resumes at block 1402. If,however, the user is authorized to make the proposed policymodification, the specified policy within the policy engine is modified(1406) (e.g. via ADMIN system 260) in accordance with the proposedpolicy modification specified by the user. Thereafter, admin procedure1400 resumes at block 1402.

In addition to responding to input from a remote user, admin procedure1400 is also responsive to input from monitor system 262. Thus, when areported problem from monitor system 262 is received (1410) at ADMINsystem 260, the admin procedure notifies (1412) the system administratorof the reported problem via terminal 266. The system administrator isthen able to analyze the problem and make modifications to the policyengine to correct the reported problem.

Illustrative Example

FIGS. 16-18 provide an illustrative example of how the various networkelements of FIG. 16 interact with each other to form the feedback-basedadaptive network of the present invention.

Referring to FIG. 16, a frame relay virtual circuit is shown connectinguser1 (1602) with user2 (1620). User1 communicates with a first router1604 via link A. In the example of FIG. 16, router 1604 may be managedby a first service provider (SP1). Router 1604 communicates with a framerelay cloud 1612 via link B and switch 1612. The frame relay cloud 1610is managed and maintained by a service provider such as AT&T. The framerelay cloud 1610 communicates with a second router 1614 via link C andswitch 1613. The second router 1614 may be managed by a second serviceprovider (SP2). User 1620 communicates with router 1614 via link D.Using the network illustrated in FIG. 16, various aspects of the presentinvention will now be described by way of example in which a videoconference is established between user1 (1602) and user2 (1620). Thevideo conference example is described in greater detail with respect toFIGS. 17 and 18 of the drawings.

FIG. 17 shows a flow diagram of how the feedback-based network of FIG.16 adapts to changing conditions in the network as a video conference isinitiated between user1 and user2. A video conference applicationbetween user1 and user2 is one example of a user application which mayrequire additional bandwidth in order to provide a satisfactory level ofquality for using the application to service multiple users across thenetwork. Thus, the video conference example may be abstracted to beapplied to any user application requiring additional network resourcesto provide a satisfactory level of quality for the application to runover a network environment.

As shown in FIG. 17, when a video conference between user1 and user2 isinitiated (1702), the network may respond by initiating one or morebandwidth policies at the policy engine 1654, and may also respond byinitiating one or more policies/procedures at the monitor system 1662.Thus, at 1704, the frame relay CIR policy is initiated at the policyengine 1654, if this policy has not already been initiated. For example,in a specific embodiment of the present invention, the frame relay CIRpolicy is loaded at initialization of the policy engine according toinstructions contained in a configuration file. Once loaded, this policymay run continuously and concurrently with other polices and/or userapplications. In an alternate embodiment, when the user 1602 initiates avideo conference with user 1620, this information is passed to ADMINsystem 1660. Recognizing that the video conference application mayrequire an increase in allotted bandwidth, ADMIN system 1660 instructspolicy engine 1654 to initiate the frame relay CIR policy.

While the frame relay CIR policy is being initiated by the policy engineat 1704, a CIR policy monitor procedure is concurrently initiated (1716)at monitor system 1662, if this procedure has not already beeninitiated. The monitor system 1662 may load the CIR policy monitorprocedure at initialization in accordance with instructions contained inan initialization configuration file related to monitor system 1662.Alternatively, notice of the initiation of the video conferenceapplication may be provided by either one of the users to the ADMINsystem 1660. The ADMIN system then instructs the monitor system 1662 toload and execute the CIR policy monitor procedure.

One purpose of the frame relay CIR policy (implemented by policy engine1654) is to monitor the number of packets dropped on selected links inthe network, and to adjust or modify the CIR parameter values on theselinks dynamically and automatically in response to changing networkconditions. One purpose of the CIR policy monitor procedure (implementedby monitor system 1662) is to evaluate the effectiveness of the framerelay CIR policy. Thus, both procedures/policies may run concurrentlyand, if desired, continuously.

At 1706, each of the links A, B, C, D of FIG. 16 reports the number ofpackets dropped on that link (typically reported as the number ofpackets dropped during a specified time period) to data store 1652. Theframe relay CIR policy at the policy engine 1654 uses this data togenerate (1708) updated CIR parameter values for each of the respectivelinks. The updated CIR parameter values generated by the policy engineare then written (1710) into the data store 1652. The event handler 1672identifies the updated CIR parameter values as new events, and notifies(1712) the appropriate network elements in the network of changedconditions in the network. Notification of the appropriate networkelements may be accomplished via the event server 1670, which maybroadcast the event notification message relating to the changed networkconditions to those network elements which have registered to receivethis type of event notification message.

Once the appropriate network elements have been notified of the changednetwork conditions, each of the appropriate network elements mayretrieve its respective updated CIR parameter information from the datastore 1652, and may then update (1714) its configuration utilizing theupdated CIR parameter information retrieved from the data store. Thus,for example, the CIR values used by the router one (1604, FIG. 16) maybe modified using the updated CIR parameter data to increase or decreasedata traffic.

Presumably, the updating of the CIR parameter values in each of theselected network elements will affect the number of packets dropped oneach of the links associated with these network elements. Thus, afterthe appropriate network elements have been updated or re-configuredutilizing the updated CIR parameter values, the adaptivefeedback-control process resumes at block 1706, whereupon each of thelinks A, B, C, D provides updated information to the data store relatingto the respective number of packets dropped at each link. This updatedinformation is then analyzed by the policy engine to generate new CIRparameter values, (if necessary) to be implemented by the appropriatenetwork elements. This adaptive feedback-control process continues untilthe reported number of packets dropped by each of the respective linksconforms with predetermined criteria. When this occurs, the policyengine may still evaluate the number of packets dropped at eachrespective link, but it will no longer need to generate new CIRparameter values since the current network parameters will reflect thatthe network has adequately adapted to the current network conditions. Inan alternate embodiment, the policy engine still generates the updatedCIR parameter values (even if these values are the same as the valuesreported by the network elements), and writes these values into datastore 1652. However, the event handler 1672 recognizes that the current(i.e. reported) CIR values are the same as the desired (i.e. updated)CIR values, and does not notify the network elements of the event. Eventnotification will be triggered when the event handler 1672 detects adifference between the current and desired CIR values.

In the CIR policy monitor procedure of FIG. 17, the quality monitorsystem 1662 (FIG. 16) may concurrently and continuously monitor theeffectiveness of the frame relay CIR policy implemented by the policyengine. In the example of FIG. 17, the effectiveness of the frame relayCIR policy is measured by analyzing the number of packets dropped ateach of the respective links A, B, C. D, and comparing this data topredetermined criteria or guidelines. Thus, for example, at 1718, thereported number of packets dropped for links A, B, C, D are analyzed andcompared to a predetermined threshold in order to evaluate theeffectiveness of the frame relay CIR policy implemented by the policyengine. A determination is then made (1720) as to whether the framerelay CIR policy is effective in maintaining the number of droppedpackets on each or any of the respective links below the predeterminedthreshold value. If it is determined that the current frame relay CIRpolicy is effective in maintaining the number of dropped packets on eachof the respective links below a predetermined threshold, the qualitymonitor system 1662 may wait (1722) a specified time interval (e.g.,0-30 minutes) before re-evaluating the effectiveness of the currentframe relay CIR policy by analyzing newly updated information relatingto the number of packets dropped at each of the respective links.

If, however, it is determined that the current frame relay CIR policy isnot effective in maintaining the number of packets dropped at any of thelinks A, B, C, D below a predetermined threshold, then at 1724, adetermination is made as to whether the frame relay CIR policy should bere-evaluated. It may preferable to wait a specified amount of time inorder to allow the adaptive feedback process of the present invention toarrive at a steady state. Accordingly, in a specific embodiment of thepresent invention, the policy implemented by the policy engine may beallowed to execute a number of times before action is taken to modifythe policy. For example, the current policy implemented by the policyengine, even if judged ineffective, may be allowed to execute from 0-5hours before action is taken to modify the policy. Alternatively, thecurrent policy may be re-evaluated if it is determined that the currentpolicy is improving an aspect of the network performance. For example,if the number of reported packets dropped for one or more of therespective links show a reduction compared to that of previous reports,the current frame relay CIR policy may be allowed to continue withoutmodification.

Accordingly, if is determined that the current frame relay CIR policy isto be re-evaluated, monitor system 1662 waits (1722) a specified timeinterval before re-evaluating the effectiveness of the policy. However,if it is determined that the current frame relay CIR policy is not to bere-evaluated at 1726, the ADMIN system 1660 is notified of theineffective frame relay CIR policy. Thereafter, at 1728, the frame relayCIR policy may be dynamically modified via ADMIN system 1660. Asdescribed previously, the dynamic modification of a policy within thepolicy engine may be implemented manually by a system administrator viaconsole 1666 or, alternatively, it may be implemented automatically bythe ADMIN system using artificial intelligence and/or fuzzy logic. Inthe current example, the frame relay CIR policy may be dynamicallymodified by modifying the formula which the policy uses to compute theupdated CIR parameter values. An example of how the frame relay CIRpolicy may be modified is discussed previously, with respect to FIG. 12.Using internal logic, the variable K (taken from the formula provided inthe description of FIG. 12) may be incremented by a fixed amount (e.g.,0.1-1.0) if it is detected that the dropped packet count for arespective link exceeds the predetermined threshold value despite thecurrent frame relay CIR policy's attempt to reduce the dropped packetcount.

Thus, in a specific embodiment, the policy-based adaptive controltechnique of the present invention continually tunes at least a subsetof network elements in the network. The tuning of a network element maythen affect the policy that was used to tune the network device. Themodified policy is then used to effect future changes in the networkelements. This process repeats itself as the network adapts to changingnetwork conditions.

It will be appreciated that, since the policy engine 1654 and qualitymonitor 1662 may each be implemented as multi-thread processes or singlethread processes with multiple runtime instances, other policies and/orquality monitoring procedures may be running concurrently with the framerelay CIR policy and CIR policy monitor procedure described in FIG. 17.An example of a concurrent quality monitoring procedure implemented byquality monitor system 1662 is shown in FIG. 18 of the drawings.

FIG. 18 shows an example of a flow diagram for a Service Level Agreement(SLA) analysis procedure 1800 which may be implemented by the monitorsystem 1662 of FIG. 16. One purpose of the SLA analysis procedure is tomonitor various aspects of the frame relay virtual circuit (e.g., CIR,EIR, dropped packets, Be, Bc, etc.) to ensure that these parameters fallwithin specified guidelines set forth in the Service Level Agreementestablished between the service provider and the user or client. The SLAanalysis procedure may be implemented, for example, upon initializationof the monitor system 1662. The specific guidelines or criteria setforth in the Service Level Agreement may be stored, for example, in aconfiguration file residing at the monitor system 1662. A description ofthe service level agreement analysis procedure 1800 is provided belowusing the network example of FIG. 16.

Referring to FIG. 18, at 1804, each of the links A, B, C, D (FIG. 16)reports its respective service level parameter data to data store 1652.In a specific embodiment of the present invention, the service levelparameter data is a subset of the state data or other informationreported by each of the links to the data store. The reported servicelevel parameters are then analyzed (1806) by the monitor system andcompared to values specified by the Service Level Agreement. Thecorresponding values specified by the Service Level Agreement may bestored, for example, in a configuration file which is associated withthe service level agreement analysis procedure 1800.

A determination is then made (1808) as to whether the reported servicelevel parameters associated with the virtual circuit being analyzed meetor exceed the corresponding values or criteria specified by the ServiceLevel Agreement. If it is determined that the reported service levelparameters do meet or exceed the corresponding values or standardsspecified by the Service Level Agreement, the monitor device 1662 waits(1810) a specified time interval (e.g., 0-30 minutes) before reanalyzingthe virtual circuit based upon updated service level parameters reported(1804) from the circuit elements.

If, however, it is determined that the reported service level parametersdo not meet or conform with the corresponding values or standardsspecified by the SLA, a determination is then made (1812) as to whetherthe virtual circuit should be re-analyzed using the service levelagreement analysis procedure 1800. There may be a variety of reasons fordeciding to repeat a specific analysis procedure at monitor system 1662before reporting a detected problem to the ADMIN system 1660. Forexample, it may be desirable to wait a specified time period beforereporting an error or modifying a policy in order to allow thefeedback-based control network of the present invention to adapt to thechanging network conditions and arrive at a steady state. A moredetailed discussion of this topic may be found in the discussionrelating to block 1724 of FIG. 17. If it is determined that the servicelevel parameters should be reanalyzed, the monitor system 1662 may wait(1810) a specified time interval before repeating the service levelagreement analysis procedure using newly updated service level parameterdata reported from the virtual circuit elements.

If, however, it is determined that the service level quality of thevirtual circuit is not to be re-analyzed, the ADMIN system 1660 is thennotified (1814) of the inability of the virtual circuit to conform withthe criteria or guidelines specified by the Service Level Agreement. TheADMIN system 1660 may, in turn, report (1816) the SLA problem to asystem administrator (via console 1666). Once alerted to the problem,the system administrator may manually reconfigure various networkelements in order to rectify the problem. Additionally, the ADMIN system1660 may also report (1816) the SLA problem to the client (e.g., user1602, user 1620) so that client may take appropriate action, if desired.

Even after the SLA problem has been reported via ADMIN system 1660 tothe system administrator and/or client, the monitor system 1662 maycontinue to perform SLA quality analysis of the selected virtual circuitby repeating the service level agreement analysis procedure, asdescribed in FIG. 18.

Although several preferred embodiments of this invention have beendescribed in detail herein with reference to the accompanying drawings,it is to be understood that the invention is not limited to theseprecise embodiments, and at various changes and modifications may beeffected therein by one skilled in the art without departing from thescope of spirit of the invention as defined in the appended claims.

It is claimed:
 1. A method for providing dynamic feedback control ofnetwork elements in a data network, the data network including aplurality of network elements, each of said network elements having aplurality operating parameters associated therewith, said methodcomprising: dynamically receiving information related to a first subsetof network elements; dynamically determining, using at least a portionof said received information, whether a performance of at least aportion of said network conforms with a predetermined criteria;automatically reporting, by a device having at least one processor,results of said determining to an administration system for dynamicallyresponding to said results, wherein the reporting is dynamicallytriggered in response to a determination that the performance of theportion of said network fails to conform with the predeterminedcriteria, wherein the response is selected to dynamically alter aperformance policy of the portion of the network to conform with thepredetermined criteria; and automatically and dynamically altering aperformance policy of the portion of the network to conform with thepredetermined criteria in response to a determination that theperformance of the portion of said network fails to conform with thepredetermined criteria; wherein the predetermined criteria relates to aspecified bandwidth usage.
 2. The method of claim 1 further comprising:determining that the performance of at least a portion of said networkconforms with the predetermined criteria; and delaying taking action toalter the performance policy after it has been determined that theperformance of at least a portion of said network conforms with thepredetermined criteria.
 3. The method of claim 1 wherein the performancepolicy comprises a set of rules for analyzing specific information fromselected network elements, and for generating updated controlinformation in response to analysis of the information.
 4. The method ofclaim 1 wherein said received information includes operating parameterinformation related to said first subset of network elements; andwherein said determining includes analyzing at least a portion of saidoperating parameter information to determine whether a service qualityof a portion of said network conforms with acceptable service levelparameters.
 5. The method of claim 4 further including: modifying aconfiguration of at least one network element in response to adetermination that said service quality of said network portion does notmeet a specified service level requirement, wherein the modification isselected so that the at least one network element is caused to meet thespecified service level requirement.
 6. The method of claim 1 whereinsaid determining includes analyzing said information to determinebilling information associated with a portion of said network.
 7. Themethod of claim 1 wherein said determining includes analyzing saidinformation to detect any security violations related to a portion ofsaid network.
 8. The method of claim 1 wherein said determining includesanalyzing said information to evaluate a fault management performance ofa portion of said network.
 9. The method of claim 1, wherein the networkfurther including a policy engine having at least one policy foranalyzing information from selected network elements and dynamicallygenerating updated element control parameters used to affect at leastone aspect of network performance, the method further comprising:dynamically modifying said at least one policy in response to adetermination that said policy is not effective in affecting said aspectof network performance to conform with said predefined performancecriteria.
 10. The method of claim 9 further including: reporting anon-effective policy evaluation to the system administrator.
 11. Themethod of claim 1 further including: receiving instructions from aremote user relating to a modification of a policy within said policyengine; determining whether said remote user has authorization toimplement said policy modification; and dynamically modifying saidpolicy in accordance with said user instructions.
 12. The method ofclaim 1, wherein the performance policy comprises protocol specificrules, business logic rules, event notification rules, or a combinationthereof.
 13. The method of claim 1, wherein the performance policy isstored in a policy library.
 14. The method of claim 1 furthercomprising: automatically reporting results of said determining to asystem administrator in response to a determination that performance ofthe portion of said network fails to conform with the predeterminedcriteria; and receiving instructions from said system administrator formodifying said performance policy.
 15. An apparatus comprising: at leastone CPU; memory; and at least one interface for dynamically receivinginformation related to a first subset of network elements; the apparatusbeing configured to: dynamically determine, using at least a portion ofsaid received information, whether a performance of at least a portionof said network conforms with a predetermined criteria; automaticallyreport results of said determining to an administration system fordynamically responding to said results, wherein the reporting isdynamically triggered in response to a determination that theperformance of the portion of said network fails to conform with thepredetermined criteria, wherein the response is selected to dynamicallyalter a performance policy of the portion of the network to conform withthe predetermined criteria; and automatically and dynamically alter aperformance policy of the portion of the network to conform with thepredetermined criteria in response to a determination that theperformance of the portion of said network fails to conform with thepredetermined criteria; wherein the predetermined criteria relates to aspecified bandwidth usage.
 16. A system for providing dynamic feedbackcontrol of network elements in a data network, the data networkincluding a plurality of network elements, each of said network elementshaving a plurality operating parameters associated therewith, saidsystem comprising: at least one processor; at least one interfaceconfigured to provide a communication link to at least one other networkdevice in the data network; and memory; the system being configured to:dynamically receive information related to a first subset of networkelements; dynamically determine, using at least a portion of saidreceived information, whether a performance of at least a portion ofsaid network conforms with a predetermined criteria; automaticallyreport results of said determining to an administration system fordynamically responding to said results, wherein the reporting isdynamically triggered in response to a determination that theperformance of the portion of said network fails to conform with thepredetermined criteria, wherein the response is selected to dynamicallyalter a performance policy of the portion of the network to conform withthe predetermined criteria; and automatically and dynamically alter aperformance policy of the portion of the network to conform with thepredetermined criteria in response to a determination that theperformance of the portion of said network fails to conform with thepredetermined criteria; wherein the predetermined criteria relates to aspecified bandwidth usage.
 17. The system of claim 16 being furtherconfigured to: determine that the performance of at least a portion ofsaid network conforms with the predetermined criteria; and delay takingaction to alter the performance policy after it has been determined thatthe performance of at least a portion of said network conforms with thepredetermined criteria.
 18. The system of claim 16 wherein theperformance policy comprises a set of rules for analyzing specificinformation from selected network elements, and for generating updatedcontrol information in response to analysis of the information.
 19. Thesystem of claim 16 wherein said received information includes operatingparameter information related to said first subset of network elements,the system being further configured to: analyze at least a portion ofsaid operating parameter information to determine whether a servicequality of a portion of said network conforms with acceptable servicelevel parameters.
 20. The system of claim 19 being further configuredto: modify a configuration of at least one network element in responseto a determination that said service quality of said network portiondoes not meet a specified service level requirement, wherein themodification is selected so that the at least one network element iscaused to meet the specified service level requirement.
 21. The systemof claim 20 being further configured to: analyze said information todetermine billing information associated with a portion of said network.22. The system of claim 16 being further configured to: analyze saidinformation to detect any security violations related to a portion ofsaid network.
 23. The system of claim 16 being further configured to:analyze said information to evaluate a fault management performance of aportion of said network.
 24. The system of claim 16, wherein the networkfurther includes a policy engine having at least one policy foranalyzing information from selected network elements and dynamicallygenerating updated element control parameters used to affect at leastone aspect of network performance, the system being further configuredto: dynamically modify said at least one policy in response to adetermination that said policy is not effective in affecting said aspectof network performance to conform with said predefined performancecriteria.
 25. The system of claim 24 being further configured to: reporta non-effective policy evaluation to the system administrator.
 26. Thesystem of claim 16 being further configured to: receive instructionsfrom a remote user relating to a modification of a policy within saidpolicy engine; determine whether said remote user has authorization toimplement said policy modification; and dynamically modify said policyin accordance with said user instructions.
 27. A system for providingdynamic feedback control of network elements in a data network, the datanetwork including a plurality of network elements, each of said networkelements having a plurality operating parameters associated therewith,said system comprising: a hardware network device operable todynamically receive information related to a first subset of networkelements; means for dynamically determining, using at least a portion ofsaid received information, whether a performance of at least a portionof said network conforms with a predetermined criteria; means forautomatically reporting results of said determining to an administrationsystem for dynamically responding to said results, wherein the reportingis dynamically triggered in response to a determination that theperformance of the portion of said network fails to conform with thepredetermined criteria, wherein the response is selected to dynamicallyalter a performance policy of the portion of the network to conform withthe predetermined criteria; and means for automatically and dynamicallyaltering a performance policy of the portion of the network to conformwith the predetermined criteria in response to a determination that theperformance of the portion of said network fails to conform with thepredetermined criteria; wherein the predetermined criteria relates to aspecified bandwidth usage.
 28. The system of claim 27 furthercomprising: means for determining that the performance of at least aportion of said network conforms with the predetermined criteria; andmeans for delaying taking action to alter the performance policy afterit has been determined that the performance of at least a portion ofsaid network conforms with the predetermined criteria.
 29. The system ofclaim 27 wherein the performance policy comprises a set of rules foranalyzing specific information from selected network elements, and forgenerating updated control information in response to analysis of theinformation.